public class User {
    private String Account;
    private String Password;
    private String Mailbox;

    public User(String requiredAccount, String requiredPassword, String optionalMailbox) {
        this.Account = requiredAccount;
        this.Password = requiredPassword;
        this.Mailbox = (optionalMailbox != null) ? optionalMailbox : " ";
    }

    public User(String requiredAccount, String requiredPassword) {
        this(requiredAccount, requiredPassword, " ");
    }

    public String getAccount() {
        return Account;
    }

    public String getPassword() {
        return Password;
    }

    public String getMailbox() {
        return Mailbox;
    }


    public static void main(String[] args) {
        User user1 = new User("Yugo", "123456", "yugo@foxmail.com");
        User user2 = new User("MYQ", "654321");

        System.out.println("Account1 = " + user1.getAccount());
        System.out.println("Password1 = " + user1.getPassword());
        System.out.println("Mailbox1 = " + user1.getMailbox());
        System.out.println("Account2 = " + user2.getAccount());
        System.out.println("Password2 = " + user2.getPassword());
    }

}
